" 'The Department of State has instructed certain US embassies and consulates to remain closed or to suspend operations on Sunday, August 4,' Harf told reporters.

"The decision was taken 'out of an abundance of caution and care for our employees and others who may be visiting our installations,' she said.

"Harf said that the embassies would be closed specifically on Sunday, with an assessment afterwards on whether to reopen them."

The State Department has not released a list of which embassies will be closed. This of course, brings to mind the attack on the U.S. consulate in Benghazi, Libya, which left four Americans dead, including Ambassador Christopher Stevens.

Update at 6:40 p.m. ET. All U.S. Embassies, Consulates Closed:

The State Department tells NPR's Michelle Kelemen that they have asked all of their embassies and consulates normally open on Sunday to close on Aug. 4.

A senior State Department official said:

"It is possible we may have additional days of closing as well. Again as Marie said at the briefing, the Department has been apprised of information that indicates we should institute these precautionary steps. We have taken this measure out of an abundance of caution and care for our employees and others who may be visiting our installations. The Department, when conditions warrant, takes steps like this to balance our continued operations with security and safety."